FIELD OF THE INVENTION
The field of art to which this invention pertains is aromatic polyamide fibers and, more particularly, it is directed to a process for stabilizing such fibers using readily available commercial equipment.
Specifically, such invention is a substantially amorphous, aromatic polyamide fiber containing a surfactant in an amount sufficient to enable the fiber to be dyed a deep shade. More specifically, the fiber must contain from about 5 to 15% of the surfactant, by weight, to be effective. This high surfactant content enables the fiber, in fabric form, to be stabilized against progressive laundry shrinkage, at low temperatures, by use of later routine processing steps, utilizing equipment found in a typical plant, without requiring the use of a carrier.
A typical routine processing step which provides improved stabilization in the surfactant-containing fiber comprises:
heating the amorphous fiber, under pressure, in an aqueous stabilizing bath heated to a low temperature of less than 130.degree. C., and preferably to a temperature of about 127.degree. C., to crystallize it. A dye may be added to the bath and the amorphous fiber may be simultaneously dyed and crystallized in such bath.
Another processing step for stabilizing such fiber comprises:
treating the amorphous fiber, under pressure, with steam heated to a temperature of less than 150.degree. C., and preferably about 145.degree. C., whereby to crystallize such fiber.
The surfactant is imbibed into the fiber while it is water-swollen and prior to drying. A dye may be imbibed into the fiber prior to imbibition of the surfactant. After drying the dyed fiber may be printed with another dye and thereafter treated, under pressure, with steam heated to a temperature of about 145.degree. C. to stabilize it, while simultaneously setting the printed dye.